TWI389371B - Electrolyte liquid composition for photoelectric conversion device and photoelectric conversion device using the same - Google Patents

Description

Electrolyte composition for photoelectric conversion element and photoelectric conversion element using the same

The present invention relates to a photoelectric conversion element. More specifically, the present invention relates to an electrolyte composition for a photoelectric conversion element having excellent electrical properties, and a photoelectric conversion element using the same.

Solar cells, which are highly regarded as clean energy sources, have been used in general housing in recent years. However, it has not been fully popularized. The reason is that the performance of the solar cell itself is difficult to be said to be sufficiently superior, so that a large number of components cannot be obtained, and the solar cell itself is expensive due to low productivity of component manufacturing.

There are many types of solar cells, and most of the practical solar cells are solar cells. Recently, a dye-sensitized wet solar cell that has been researched for its practical use has been attracting attention. The dye-sensitized wet solar cell system has been researched since the early days. The basic structure is composed of an oxide semiconductor, a dye adsorbed thereon, an electrolyte solution, and a counter electrode. Among them, there are various reviews on pigments or electrolytic solutions, and research on semiconductors is extremely limited. In other words, the initial dye-sensitized wet solar cell was studied with a single crystal electrode of a semiconductor. Specific examples of the single crystal electrode include titanium oxide (TiO ₂ ), zinc oxide (ZnO), cadmium sulfide (CdS), and tin oxide (SnO ₂ ). However, since the single-crystal electrode has a small dye adsorption energy, the conversion efficiency is extremely low, and the cost is high. The improvement proposal is to sinter the fine particles and set a large number of fine-hole high-surface-area semiconductors. In the case of the use of such a porous zinc oxide electrode which adsorbs an organic pigment, the performance of the electrode is very high (Patent Document 1).

Then, in 1991, Guleijielu (Switzerland) developed a light (solar) battery using a photoelectric conversion element called a dye-sensitized solar cell. This is also known as the Gulei Jielu battery. The structure is a sensitization of a dye on a transparent conductive substrate, and a film substrate made of oxide semiconductor fine particles formed on one of the electrodes and a counter electrode of a reducing agent such as platinum disposed opposite thereto Between the substrates, the charge transporting layer (electrolyte containing the redox species) is held. For example, by adsorbing a ruthenium complex dye on a porous titanium oxide electrode, it has a performance in parallel with a ruthenium solar cell (Non-Patent Document 1). However, in the case of the dye-sensitized solar cell, a significant improvement effect cannot be obtained in the improvement of the energy conversion efficiency. In order to make the dye-sensitized solar cell which replaces the above-mentioned costly solar cell practical, it is preferable to improve the photoelectric conversion efficiency and the like in the dye-sensitized solar cell.

Therefore, from the viewpoint of improving the photoelectric conversion efficiency, the electrolyte medium used in the charge-transfer layer of the dye-sensitized solar cell has an electrolyte-to-solution in which an electrolyte pair is dissolved in an organic solvent. However, the use of an electrolyte-to-solution for the electrochemical conversion element of the charge-transporting layer causes a liquid leakage between use or storage for a long period of time, resulting in a problem of lack of reliability. Non-Patent Document 1 and Patent Document 2 include a photoelectric conversion element using semiconductor fine particles sensitized by a dye, and a photoelectrochemical cell using the same. However, an electrolyte-containing solution containing an organic solvent is also used in the charge transporting layer. Therefore, between long-term use or storage, the electrolyte may leak or thirst. As a result, the photoelectric conversion efficiency is remarkably lowered, and there is a loss of function as a photoelectric conversion element.

Under this circumstance, there is a proposal to use a photoelectric conversion element of a solid electrolyte pair. For example, Patent Document 3 and Non-Patent Document 2 disclose a photoelectric conversion element including a solid electrolyte pair using a crosslinked polyethylene oxide polymer compound. However, the use of such a solid electrolyte for the photoelectric conversion element has insufficient photoelectric conversion characteristics, especially short-circuit current density, and insufficient durability.

In addition, in order to prevent the leakage of the electrolyte, the thirst, and the durability, there is a method of using a pyridinium salt, an imidazolium salt, a triazolium salt or the like as an electrolyte to salt (Patent Document 4, Patent Document 5, etc.). These salts are in a liquid state at room temperature and are referred to as room temperature molten salts. This method uses a normal temperature molten salt having a small vapor pressure as a solvent to improve the durability of the battery. However, the photoelectric conversion element using such a room temperature molten salt has a problem that the open voltage is low and the photoelectric conversion efficiency is insufficient.

Patent Document 1: Patent No. 2,664, 194 Patent Document 2: U.S. Patent No. 4,927,721, Patent Document 3: Japanese Patent Publication No. Hei 07-288142, Patent Document 4: WO-95/18456, Patent Document 5: JP-A 08-259543 Bulletin

Non-Patent Document 1: Nature, Vol. 353, pp. 737-740, Non-Patent Document 2, 1991: J. Am. Chem. Soc, 115 (1993), 6382 Non-Patent Document 3: Solid State Ionics, 89, 263 (1996) )

The present invention provides an electrolyte composition which can realize both high photoelectric conversion efficiency and durability in a dye-sensitized photoelectric conversion element, and a photoelectric conversion element which is used for a charge-transporting layer, and further uses a solar cell thereof Main purpose (subject).

In order to solve the above problems, the inventors of the present invention have found that by using an electrolyte composition containing a specific normal temperature molten salt and an organic solvent having no ionicity as a charge transporting layer, it has been found through intensive investigation and continuous research. The above issues. The present invention has been completed.

That is, the present invention relates to the following constituents.

[1] An electrolyte composition for a photoelectric conversion element, which comprises a redox electrolyte pair, a room temperature molten salt, and an organic solvent which is not ionic; and a total weight of a normal temperature molten salt and an ionic organic solvent; The ratio of the nonionic organic solvent is 2 to 40% by weight.

[2] The electrolyte composition for a photoelectric conversion element according to [1], wherein the cation forming the normal temperature molten salt is a cation having a quaternary ammonium group represented by the formula (1),

[In the formula (1), R _{1 1} , R _{1 2} , R _{1 3} and R _{1 4} are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms or an alkoxyalkyl group having 2 to 8 carbon atoms] .

[3] The electrolyte composition for a photoelectric conversion element according to [1], wherein a cation which forms a normal temperature molten salt is a scorpion or a scorpion having one or two nitrogen atoms and atoms other than a nitrogen atom. A cyclic quaternary ammonium group cation.

[4] The electrolyte composition for a photoelectric conversion element according to [3], wherein the cation having a cyclic quaternary ammonium group is a cation represented by the following formula (2).

In the formula (2), R _{2 1} and R _{2 2} are each independently an alkyl group having 1 to 8 carbon atoms; and R _{2 3} is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

[5] The electrolyte composition for a photoelectric conversion element according to [3], wherein the cation having a cyclic quaternary ammonium group is a cation represented by the following formula (3).

[In the formula (3), R _{3 1} and R _{3 2} are each independently an alkyl group having 1 to 8 carbon atoms; and R _{3 3} to R _{3 6} are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms] .

[6] The electrolyte composition for a photoelectric conversion element according to [3], wherein the cation having a cyclic quaternary ammonium group is a cation represented by the following formula (4).

[In the formula (4), R _{4 1} is an alkyl group having 1 to 8 carbon atoms; and R _{4 2} to R _{4 8} are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms].

[7] The electrolyte composition for a photoelectric conversion element according to [3], wherein the cation having a cyclic quaternary ammonium group is a cation represented by the following formula (5).

[In the formula (5), R _{5 1} is an alkyl group having 1 to 8 carbon atoms; and R _{5 2} to R _{5 6} are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms].

[8] The electrolyte composition for a photoelectric conversion element according to [3], wherein the cation having a cyclic quaternary ammonium group is a cation represented by the following formula (6).

[In the formula (6), R _{6 1} and R _{6 2} are each independently an alkyl group having 1 to 8 carbon atoms; and R _{6 3} to R _{7 0} are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms] .

[9] The electrolyte composition for a photoelectric conversion element according to [3], wherein the cation having a cyclic quaternary ammonium group is a cation represented by the following formula (7).

[In the formula (7), R ^{7 1} is an alkyl group having 1 to 8 carbon atoms; and R _{7 2} to R _{7 6} are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms].

[10] A photoelectric conversion element comprising: a conductive support having a semiconductor-containing layer; and a conductive support having opposite electrodes disposed at a predetermined pitch, wherein the charge-moving layer is held by the gap between the two supports In the photoelectric conversion element, the charge-transporting layer contains the electrolyte composition for a photoelectric conversion element according to any one of the items [1] to [9].

[11] The photoelectric conversion element according to [10], wherein the semiconductor of the semiconductor-containing layer is titanium oxide.

[12] The photoelectric conversion element according to [11], wherein the titanium oxide is a modified titanium oxide.

[13] The photoelectric conversion element according to [11] or [12] wherein the titanium oxide is a particulate titanium oxide formed by dye sensitization.

[14] The photoelectric conversion element according to [13], wherein the dye is a metal complex dye or a non-metal organic dye.

[15] A solar cell comprising the photoelectric conversion element according to any one of [10] to [14].

The electrolyte composition for a photoelectric conversion element of the present invention is very suitable for a secondary battery such as a photoelectric conversion element or a fuel cell, a battery such as a lithium battery or an electric double layer capacitor. In particular, high photoelectric conversion efficiency can be obtained by using the photoelectric conversion element thereof to obtain a large short-circuit current. Further, since the molten salt at normal temperature is used, there is no leakage or the like, and there is an advantage that the durability of the photoelectric conversion element is improved. Therefore, the solar cell obtained by the photoelectric conversion element has high conversion efficiency and superior durability, and has a low cost effect.

[Embodiment of the Invention]

DETAILED DESCRIPTION The present invention is as follows.

The electrolyte composition for a photoelectric conversion element of the present invention contains a redox-based electrolyte pair, a normal-temperature molten salt, and an organic solvent which is not ionic; and has no ionic organic matter with respect to the total weight of the normal-temperature molten salt and the non-ionic organic solvent. The solvent ratio is 2 to 40% by weight, preferably 5 to 40% by weight. The photoelectric conversion element of the present invention comprises a conductive support of a semiconductor-containing layer and a conductive support having opposite electrodes disposed at a predetermined pitch, and a charge-transporting layer is formed in a space between the two supports. More specifically, at least one of them is a conductive support having a semiconductor-containing layer for adsorbing a dye for sensitization on a conductive support such as a transparent conductive glass, and a conductive support having a counter electrode disposed opposite to a predetermined pitch. The body is held by the charge moving layer in the gap between the two supports. Further, in the charge transporting layer, the electrolyte composition for a photoelectric conversion element of the present invention is used.

First, the electrolyte composition for a photoelectric conversion element of the present invention will be described.

The electrolyte composition of the present invention is a mixture of a redox electrolyte pair and a normal temperature molten salt and an organic solvent which is not ionic. The term "normal temperature molten salt" as used herein refers to an ionic compound which exhibits at least a portion of a liquid at room temperature. The room temperature molten salt is preferably a molten salt formed of a quaternary ammonium cation and an anion formed only of a non-metal element. The term "normal temperature" as used herein refers to a temperature range in which the device is normally operated; the upper limit is 100 ° C, usually 60 ° C, and is lowered to -50 ° C, usually -20 ° C. Further, various inorganic molten salts such as Li ₂ CO ₃ -Na ₂ CO ₃ -K ₂ CO ₃ used for electrolysis and the like have a melting point of more than 300 ° C. These inorganic molten salts are not liquid in the above temperature range in which the electrochemical device is normally operated, and are not included in the so-called normal temperature molten salt of the present invention.

The cation which forms the normal temperature molten salt used in the present invention, has a cation having a quaternary ammonium group having a skeleton represented by the above formula (1), and has a lanthanum or headland composed of atoms other than 1 to 2 nitrogen atoms and nitrogen atoms. The cyclic quaternary ammonium group cation is preferred.

In the formula (1), R _{1 1} , R _{1 2} , R _{1 3} and R _{1 4} are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms or an alkoxyalkyl group having 2 to 8 carbon atoms. . The preferred alkyl group is a linear, branched or cyclic alkyl group having 1 to 7 carbon atoms, more preferably a linear alkyl group having 1 to 6 carbon atoms. Specific examples of the alkyl group are methyl, ethyl, vinyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, tert-butyl, cyclobutyl, n-pentyl, 2-methyl Butyl, 3-methylbutyl, 3-ethylpropyl, 2,2-dimethylpropyl, 2,3-dimethylpropyl, n-hexyl, 2-methylpentyl, 3- Methylpentyl, 4-methylpentyl, 5-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 2,4-dimethylbutyl, 3, 3-dimethylbutyl, 3,4-dimethylbutyl, 4,4-dimethylbutyl, cyclohexyl, n-heptyl, 2-methylhexyl, 3-methylhexyl, 4-methyl Hexyl, 5-methylhexyl, 6-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 2,5-di Methylpentyl, 3,4-dimethylpentyl, 3,5-dimethylpentyl, 4,4-dimethylpentyl, 4,5-dimethylpentyl, 5,5-di Methylpentyl, 3-ethylpentyl, 4-ethylpentyl, 5-ethylpentyl, 4-propylbutyl, n-octyl, 2-methylheptyl, 3-methylheptyl , 4-methylheptyl, 5-methylheptyl, 6-methylheptyl, 7 -methylheptyl, 2,2-dimethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5-dimethylhexyl, 2,6-dimethylhexyl , 3,3-dimethylhexyl, 3,4-dimethylhexyl, 3,5-dimethylhexyl, 3,6-dimethylhexyl, 4,4-dimethylhexyl, 4,5- Dimethylhexyl, 4,6-dimethylhexyl, 5,5-dimethylhexyl, 5,6-dimethylhexyl, 6,6-dimethylhexyl, 3-ethylhexyl, 4-B Hexyl, 5-ethylhexyl, 6-ethylhexyl, 3,3-diethylbutyl, 3,4-diethylbutyl, 4,4-diethylbutyl, 4-propylpentyl , 5-propylpentyl, 2-methyl-3-isopropylbutyl, 2,2-dicyclopropylethyl, 2,2-dimethyl-(3-isopropyl)propyl Wait. Preferred alkyl groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, 2-methylbutyl, 3-methylbutyl, 3-ethylpropyl, 2,2-dimethylpropyl, 2,3-dimethylpropyl, n-hexyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 2,4-Dimethylbutyl, 3,3-dimethylbutyl, 3,4-dimethylbutyl, 4,4-dimethylbutyl, cyclohexyl, n-heptyl, 2-methyl Hexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 6-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4 - dimethylpentyl, 2,5-dimethylpentyl, 3,4-dimethylpentyl, 3,5-dimethylpentyl, 4,4-dimethylpentyl, 4,5 - dimethylpentyl, 5,5-dimethylpentyl, 3-ethylpentyl, 4-ethylpentyl, 5-ethylpentyl, 4-propylbutyl, and the like. More preferred alkyl groups are methyl, ethyl, n-propyl, isopropyl, n-pentyl, n-hexyl.

A preferred alkoxyalkyl group is an alkoxyalkyl group having 2 to 7 carbon atoms. More preferably, it is an alkoxyalkyl group which has a carbon number of 3-4. Specific examples of the alkoxyalkyl group include a methoxymethyl group, a methoxyethyl group, a methoxypropyl group, a methoxybutyl group, a methoxypentyl group, a methoxyhexyl group, and a methoxyheptyl group. , ethoxymethyl, ethoxyethyl, ethoxypropyl, ethoxybutyl, ethoxypentyl, ethoxyhexyl, n-propoxymethyl, n-propoxyethyl, N-propoxypropyl, n-propoxybutyl, n-propoxypentyl, n-butoxymethyl, n-butoxyethyl, n-butoxypropyl, n-butoxybutyl, positive Pentyloxymethyl, n-pentyloxyethyl, n-pentyloxypropyl, n-hexyloxymethyl, n-hexyloxyethyl, n-heptyloxymethyl and the like. Preferred alkoxyalkyl groups are methoxyethyl, methoxypropyl, methoxybutyl, methoxypentyl, methoxyhexyl, ethoxymethyl, ethoxyethyl, Ethoxypropyl, ethoxybutyl, ethoxypentyl, n-propoxymethyl, n-propoxyethyl, n-propoxypropyl, n-propoxybutyl, n-butoxy Methyl, n-butoxyethyl, n-butoxypropyl, n-pentyloxymethyl, n-pentyloxyethyl, n-hexyloxymethyl and the like. More preferably, the alkoxyalkyl group is a methoxyethyl group or a methoxypropyl group.

Specific examples of the cation having a quaternary ammonium group represented by the formula (1) include a trimethylethylammonium cation, a trimethylpropylammonium cation, a trimethylhexylammonium cation, a tetraamylammonium cation, and a methyldiethyl cation. A methoxyethylammonium cation, a trimethylisopropylammonium cation, or the like.

The cation having a cyclic quaternary ammonium group of lanthanum or guanidine composed of one or two nitrogen atoms and atoms other than a nitrogen atom is preferably a cation represented by the above formulas (2) to (7). These cations may be mixed in two or more types.

R _{2 1} to R _{2 3} of the formula (2) are alkyl groups (each independently selected), and specific examples of the alkyl group are the same as those in the case where R _{1 1} to R _{1 4} of the formula (1) are alkyl groups. Specific examples. Specific examples of the preferred alkyl group of R _{2 1} to R _{2 3 are} the same as those of the preferred alkyl group of R _{1 1} to R _{1 4} of the formula (1). Specific examples of the more preferable alkyl group of R _{2 1} to R _{2 3 are} the same as those of the more preferable alkyl group of R _{1 1} to R _{1 4} of the formula (1).

Specific examples of the imidazolium cation having the formula (2) include an imidazolium cation such as a dialkylimidazolium cation or a trialkylimidazolium cation. Specific examples of the dialkylimidazolium cation include a 1,3-dimethylimidazolium cation, a 1-ethyl-3-methylimidazolium cation, a 1-methyl-3-ethylimidazolium cation, and a 1- Methyl-3-butylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-methyl-3-propylimidazolium cation, 1-methyl-3-vinylimidazolium cation, etc. . Specific examples of the trialkylimidazolium cation are 1,2,3-trimethylimidazolium cation, 1,2-dimethyl-3-ethylimidazolium cation, 1,2-dimethyl-3- A propyl imidazolium cation, a 1-butyl-2,3-dimethylimidazolium cation, or the like. However, it is not limited to these.

R _{3 1} to R _{3 6 in the} formula (3) are alkyl groups (each independently selected), and specific examples of the alkyl group are the same as those in the case where R _{1 1} to R _{1 4} of the formula (1) are alkyl groups. Specific examples. R R _{3 1} ~ R Specific examples of preferred alkyl groups of _36, and also the formula (1) of R ₁ is preferably ₁ ~ ₁₄ alkyl group are the same as specific examples, R _{3 1} ~ R _{3 6} of the more Specific examples of the preferred alkyl group are the same as those of the more preferred alkyl group of R _{1 1} to R _{1 4} of the formula (1).

Specific examples of the pyrrole ruthenium cation represented by the formula (3) include 1,1-dimethylpyrroleium cation, 1-ethyl-1-methylpyrroleium cation, and 1-methyl-1-propylpyrroleium. A cation, a 1-butyl-1-methylpyrroleium cation or the like. It is not limited to these.

R _{4 1} to R _{4 8 in the} formula (4) are alkyl groups (each independently selected), and specific examples of the alkyl group are the same as those in the case where R _{1 1} to R _{1 4} of the formula (1) are alkyl groups. Specific examples. Specific examples of the preferred alkyl group of R _{4 1} to R _{4 8 are} the same as those of the preferred alkyl group of R _{1 1} to R _{1 4} of the formula (1). Specific examples of the more preferable alkyl group of R _{4 1} to R _{4 8 are} the same as those of the more preferable alkyl group of R _{1 1} to R _{1 4} of the formula (1).

Specific examples of the pyrrole ruthenium cation represented by the formula (4) include 1,2-dimethylpyrroleium cation, 1-ethyl-2-methylpyrroleium cation, and 1-propyl-2-methylpyrroleium. A cation, a 1-butyl-2-methylpyrroleium cation or the like. It is not limited to these.

R _{5 1} to R _{5 6 in the} formula (5) are alkyl groups (each independently selected), and specific examples of the alkyl group are the same as those in the case where R _{1 1} to R _{1 4} of the formula (1) are alkyl groups. Specific examples. Specific examples of the preferred alkyl group of R _{5 1} to R _{5 6 are} the same as those of the preferred alkyl group of R _{1 1} to R _{1 4} of the formula (1). Specific examples of the more preferable alkyl group of R _{5 1} to R _{5 6 are} the same as those of the more preferable alkyl group of R _{1 1} to R _{1 4} of the formula (1).

Specific examples of the pyrazolium cation represented by the formula (5) include 1,2-dimethylpyrazolium cation, 1-ethyl-2-methylpyrazolium cation, and 1-propyl-2-methyl. Pyridyl cation, 1-butyl-2-methylpyrazolium cation, and the like. It is not limited to these.

R _{6 1} to R _{7 0} of the formula (6) are alkyl groups (each independently selected), and specific examples of the alkyl group are the same as those in the case where R _{1 1} to R _{1 4} of the formula (1) are alkyl groups. Specific examples. R _{6 1} ~ R _{7 0} R Specific examples of preferred alkyl groups, also with the formula (1) of _{1 1} ~ R ₁₄ is preferably an alkyl group the same as those specific examples. Specific examples of the more preferable alkyl group of R _{6 1} to R _{7 0 are} the same as those of the more preferable alkyl group of R _{1 1} to R _{1 4} of the formula ( ₁ ).

Specific examples of the pyrrolidinium cation represented by the formula (6) include 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, and 1-methyl-1-propene. A pyrrolidinium cation, a 1-butyl-1-methylpyrrolidinium cation, or the like. It is not limited to these.

R _{7 1} to R _{7 6 in the} formula (7) are (independently selected), and specific examples of the alkyl group are the same as those in the case where R _{1 1} to R _{1 4 in the} formula (1) are alkyl groups. By. Specific examples of the preferred alkyl group of R _{7 1} to R _{7 6 are} the same as those of the preferred alkyl group of R _{1 1} to R _{1 4} of the formula (1). Specific examples of the more preferable alkyl group of R _{7 1} to R _{7 6 are} the same as those of the more preferable alkyl group of R _{1 1} to R _{1 4} of the formula (1).

Specific examples of the pyrrolidinium cation represented by the formula (7) include N-methylpyrrolidinium cation, N-ethylpyrrolidinium cation, N-propylpyrrolidinium cation, and N-butylpyrrolidinium. A cation, a 1-ethyl-2-methylpyrrolidinium cation, a 1-butyl-4-methylpyrrolidinium cation, a 1-butyl-2,4-dimethylpyrrolidinium cation, or the like. It is not limited to these.

The cation having the quaternary ammonium group represented by the formula (1) and the cation having the quaternary ammonium group represented by the formula (2) to the formula (7), which are exemplified above, have high flame retardancy. Further, these cations have a low melting point and are liquid cations which are also called ionic liquids at normal temperature. When an electrolyte composition of a room temperature molten salt obtained by using such a cation is used, not only high ion conductivity but also high flame retardancy can be obtained.

The room temperature molten salt used in the present invention is preferably composed of the above cations and anions. The counter ion (anion) of the cation is selected from the group consisting of I ^- , BF ₄ ^- , PF ₆ ^- , SO ₃ ^- , CF ₃ SO ₃ ^- , N(CF ₃ SO ₂ ) ₂ ^- , N(C ₂ F ₅ SO _{2 2} ^- , N(CF ₃ SO ₂ )(C ₄ F ₉ SO ₂ ) ^- , C(CF ₃ SO ₂ ) ₃ ^- and C(C ₂ F ₅ SO ₂ ) ₃ ^{- are} preferred. These anions may be mixed in two or more kinds. By selecting these anions, a room temperature molten salt having a low melting point can be easily formed, and it can be a room temperature molten salt having high ion conductivity.

When the cation and the anion form a room temperature molten salt, specific examples of the preferable combination of the cation and the anion include the combinations shown in the following (1) to (4). It is not limited to these.

(1) A combination of an N-butylpyrroleium cation, a tetrafluoroborate anion (BF ₄ ^- ), a trifluoromethanesulfonate anion (CF ₃ SO ₃ ^- ), or the like.

(2) Trimethylhexyl ammonium cation, with trifluoromethanesulfonyl decylamine anion [N(CF ₃ SO ₂ ) ₂ ^- ], bis pentafluoroethane sulfonyl decylamine anion [N (C ₂ F ₅ SO ₂ ) ₂ ^- ] and so on.

(3) 1-ethyl-3-methylimidazolium cation, tetrafluoroborate anion (BF ₄ ^- ), trifluoromethanesulfonate anion (CF ₃ SO ₃ ^- ), trifluoromethanesulfonyl decylamine anion A combination of [N(CF ₃ SO ₂ ) ₂ ^- ], bis pentafluoroethane sulfonyl decylamine anion [N(C ₂ F ₅ SO ₂ ) ₂ ^- ] or the like.

(4) A combination of a 1-methyl-3-butylimidazolium cation, a tetrafluoroborate anion (BF ₄ ^- ), a hexafluorophosphate anion (PF ₆ ^- ), or the like.

In the room temperature molten salt used in the present invention, each of the cations and anions may be used, and for example, a solvent such as water may be used as needed, and the cations and anions may be mixed, stirred, and then the solvent to be used removed.

Next, the redox-based electrolyte used in the present invention is a halogen compound having a halide ion as a counter ion, a halogen redox electrolyte pair formed with a halogen molecule, or a ferrocyanate-ferrocyanate or A metal redox electrolyte pair formed by a metal complex such as a ferrocene-iron strontium ion or a cobalt complex; an alkylthiol-alkyl disulfide, a redox dye, and a hydroquinone-quinone The organic redox electrolyte is equivalent. Among these, a halogen redox electrolyte pair is preferred. The halogen molecule in the halogen redox-based electrolyte pair is, for example, an iodine molecule or a bromine molecule, and an iodine molecule is preferred. Further, a halogen compound having a halide ion as a counter ion is, for example, a metal halide such as LiI, NaI, KI, CsI, CaI ₂ or CuI; or a tetraalkylammonium iodide, imidazolium iodide or 1-methyl-3; - an organic quaternary ammonium salt of a halogen such as an alkylimidazolium iodide or pyridinium iodide. A compound (salt) having an iodide ion as a counter ion is suitable. The salt having an iodide ion as a counter ion may be, for example, lithium iodide, sodium iodide or a trimethylammonium iodide salt.

The organic solvent which is not ionic to be used in the present invention is preferably liquid at normal temperature and is not ionic. Specific examples of the organic solvent which is liquid at room temperature and which is not ionic are cyclic carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, vinyl acetate, and vinylene carbonate; γ-butyl a cyclic ester such as lactone, γ-valerolactone, propiolactone or valerolactone; a chain carbonate such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or diphenyl carbonate; a chain ester such as methyl ester, methyl acetate or methyl butyrate; tetrahydrofuran or a derivative thereof; 1,3-dioxane, 1,4-dioxane, dimethoxyethane, diethoxy Ethers such as ethane, methoxyethoxyethane, 1,2-dimethoxyethane, 1,4-dibutoxyethane, methyl diglyme; acetonitrile, 3- Nitriles such as methoxypropionitrile, methoxyacetonitrile and benzonitrile; alcohols such as ethylene glycol, propylene glycol, diethylene glycol and triethylene glycol; and dioxagens such as 1,3-dioxolane Pentylene or its derivatives; ethylene sulfide, cyclobutyl hydrazine, sultone, dimethylformamide, dimethyl hydrazine, methyl formate, 2-methyltetrahydrofuran, 3-methyl-2- Oxazolidinone, water, and the like. Among these, acetonitrile, propylene carbonate, ethylene carbonate, 3-methoxypropionitrile, methoxyacetonitrile, ethylene glycol, 3-methyl-2-oxazolidinone, γ-butyrolactone, etc. It is better. These may be used alone or in combination of two or more.

The electrolyte composition of the present invention has a ratio of the organic solvent having no ionicity to 2 to 40% by weight, preferably 5 to 40% by weight, based on the total weight of the above-mentioned normal temperature molten salt and the nonionic organic solvent. More preferably 5 to 30% by weight. With such a configuration, the photoelectric conversion efficiency of the photoelectric conversion element using the electrolytic solution composition is hardly lowered at all, and a photoelectric conversion element having good stability with time can be obtained. Moreover, with such a configuration, the ignitability of the electrolyte composition can be reduced.

Further, the electrolyte composition of the present invention has a ratio of the above-mentioned room temperature molten salt to 98 to 60% by weight, preferably 95 to 60% by weight, based on the total weight of the above-mentioned normal temperature molten salt and the nonionic organic solvent. Good is 95~70% by weight. The weight molar concentration of the redox electrolyte pair at this time is usually 0.01 to 40 parts by mole, preferably 0.05 to 20 parts by mole, more preferably 0.5 to 5 parts by mole.

The electrolyte composition for a photoelectric conversion element of the present invention having the above-described redox-based electrolyte, a room temperature molten salt, and an ionic organic solvent as essential components can be prepared, for example, by various methods described below.

That is, after dissolving the redox-based electrolyte in an organic solvent having no ionicity, it may be uniformly mixed with a normal temperature molten salt at a predetermined concentration; and, after dissolving the electrolyte pair in a normal temperature molten salt, an organic solvent having no ionicity may be added. The modulation method is not limited to this. Further, the redox-based electrolyte, the normal-temperature molten salt, and the non-ionic organic solvent may be used alone or in combination of two or more.

Further, for the purpose of improving the durability of the photoelectric conversion element, the electrolyte composition of the present invention can dissolve the low molecular gelling agent to be thickened, and can be gelled or solidified by complexing the polymer. Here, as the polymer, for example, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride or various acrylic monomers, methacrylic monomers, acrylonitrile can be used. A polymer of a monomer such as an amine monomer, an allyl monomer, or a styrene monomer. It is not limited to these. These may be used singly or in combination of two or more. These reactive components are added to the electrolyte composition, and can be reacted after the electrolyte composition injection operation described later as a gel electrolyte pair.

The electrolyte composition for a photoelectric conversion element of the present invention has a conductive support having a semiconductor-containing layer and a conductive support having a counter electrode disposed opposite to a predetermined pitch, and a charge transporting layer is sandwiched between the two supports Among the formed photoelectric conversion elements, a material which forms the charge transporting layer is suitable.

Next, the use of the electrolytic solution composition of the present invention as the charge transporting layer in the photoelectric conversion element will be described below.

Fig. 1 is a schematic cross-sectional view showing an essential part of an example of a photoelectric conversion element of the present invention. In Fig. 1, 1 is a conductive support having conductivity, 2 is a semiconductor-containing layer sensitized with a dye (referred to as a semiconductor electrode 1 and 2), and 3 is disposed on a conductive surface of a conductive support. The counter electrode, such as platinum, 4 is a charge transport layer which is disposed to be opposed to the conductive support, and 5 is a sealant. The photoelectric conversion element of the present invention is a semiconductor electrode in which a semiconductor-containing layer sensitized with a dye is disposed on a surface of a conductive support, and a counter electrode disposed opposite to a predetermined pitch, surrounded by a sealant, and the present invention is injected into the void. An electrolyte composition for a photoelectric conversion element is used as a charge transport layer.

Each of the constituent elements in the photoelectric conversion element of the present invention will be described below.

The semiconductor-containing layer is formed of metal oxide semiconductor fine particles, and a metal oxide semiconductor which can be used is an oxide of magnesium, calcium, barium or the like of a group IIa oxide of the periodic table, titanium, zirconium, hafnium of a transition metal oxide. An oxide such as lanthanum, cerium, chromium, molybdenum, niobium, tantalum, vanadium, iron, iron, silver or tungsten, an oxide of zinc of a group IIb oxide, or an oxide of aluminum or indium of a group IIIb oxide. An oxide of a group IVb oxide or an oxide of tin or the like. Among these, fine particles of a metal oxide semiconductor such as titanium oxide, zinc oxide or tin oxide are preferred. Further, the semiconductor fine particles of the metal oxide used may be a single or a mixture of two, or may be a semiconductor retoucher. As the metal oxide semiconductor fine particles, commercially available products can be used as they are, and for example, metal oxide semiconductor fine particles in which zinc oxide and tin oxide are mixed, or titanium oxide fine particles which are finished with a metal oxide or the like described below can be used.

Metal oxides which can be used for finishing titanium oxide are oxides of magnesium, calcium, barium, etc. of the oxides of Group IIa of the periodic table, zirconium, hafnium, tantalum, niobium, chromium, molybdenum, niobium, tantalum, vanadium of transition metal oxides. An oxide such as iron, nickel, silver or tungsten, an oxide such as zinc of a group IIb oxide, an oxide such as aluminum or indium of a group IIIb oxide, an oxide of a group IVb oxide, or an oxide such as tin. . Among these, it is preferred to use an oxide of magnesium, calcium, barium, zirconium, lanthanum or cerium. These metal oxides may be used alone or in combination of two or more.

The method of retouching titanium oxide can be carried out, for example, as follows.

In the production of the titanium oxide fine particles, the ratio of the metal oxides other than the titanium oxide to the titanium oxide is preferably 1/0.005 to 20 in terms of atomic ratio of titanium/non-titanium atoms, and is preferably 1/0.01 to 3 inclusive. In the preparation of the titanium oxide fine particles, the crystal system of the titanium oxide which is a raw material is used, and is not particularly limited, and an anatase crystal is preferable. The titanium oxide having anatase crystals can be obtained from the market, and can be produced by a known method from titanium alkoxide, titanium chloride, titanium sulfide, titanium nitrate or the like. It is preferred to use titanium alkoxide. As the solvent at this time, water, a water-soluble solvent or a mixed solvent thereof, or a mixed solvent of water and a water-soluble solvent can be used. In the case where the raw material is titanium alkoxide, it is preferred to use an alcohol.

In the method for producing the titanium oxide fine particles, the compound constituting each metal of each of the metal oxides is a material for refining the titanium oxide fine particles, and is, for example, a metal alkoxide, a chloride, a sulfide, or a nitrate. The resulting mixture is obtained by reacting in a solvent in a reaction vessel. Further, the metal compound is preferably an alkoxy metal. As the solvent, water, a water-soluble solvent or a mixed solvent, or a mixed solvent of water and a water-soluble solvent can be used. In the case where the starting material is an alkoxy metal, it is preferred to use an alcohol.

When the raw material is an alkoxy metal, the solvent to be used is preferably a monohydric alcohol or a polyhydric alcohol, more preferably a polyhydric alcohol, and most preferably 1,4-butanediol. The reaction temperature is preferably 110 ° C or more and 400 ° C or less. Further, after completion of the reaction, desired microparticles can be obtained by a centrifugal separation or the like. Further, after the reaction, the valve attached to the reaction vessel maintained at a temperature near the reaction temperature is opened, and the solvent is oxidized by the internal pressure, or the alcohol solvent is removed by heating under the demand, whereby fine particles can be obtained.

The titanium oxide fine particle photocatalyst can be used as a catalyst for photo-oxidation reaction, or a carrier for use as a catalyst by heat resistance, and a semiconductor-containing layer is preferably used as a dye-sensitized photoelectric conversion element. In the present invention, the titanium oxide fine particles are refined and carefully studied by the type and ratio of titanium oxide and the metal oxide compounded therein, and further by a composite method. For example, a photo-electric conversion element exhibiting a large open voltage can be obtained by a photocatalyst having high catalytic activity or sensitization with a specific sensitizing dye.

The details of the finished titanium oxide particles are as described above. Fine particles of a metal oxide such as untreated titanium oxide fine particles may be prepared by, for example, a method using the above alkoxide metal.

The semiconductor-containing layer formed of the metal oxide semiconductor fine particles is preferably a target having a high surface area for the purpose of adsorbing a dye for sensitization described later. Further, in order to achieve a high surface area of the metal oxide semiconductor fine particles, the primary particle diameter is preferably small. Specifically, the primary particle diameter is preferably from 1 to 3,000 nm, more preferably from 5 to 500 nm. The surface area of the metal oxide semiconductor fine particles can be calculated from the primary particle diameter, and is usually from 0.5 to 1,500 m ² /g, preferably from 3 to 300 m ² /g. Further, the pore volume of the metal oxide semiconductor fine particles is preferably 0.05 to 0.8 ml/g, and the average pore diameter is preferably in the range of 1 to 250 nm. In such a measurement method, for example, the surface area of the metal oxide semiconductor fine particles is measured by a nitrogen adsorption method (BET method), and the primary particle diameter is calculated from the value. Further, the average pore diameter can also be measured by the above BET method.

Next, a method of providing a film of the titanium oxide fine particles or a film of metal oxide fine particles such as titanium oxide on the conductive support will be described. Further, as the conductive support, for example, a conductive material represented by FTO (fluorine-doped tin oxide), ATO (doped tin oxide), or ITO (indium-doped tin oxide) can be used, in glass, A thin film of a substrate such as a plastic, a polymer film, a stable metal such as titanium or tantalum, or carbon. The conductivity is usually 1000 Ω/cm ² or less, preferably 100 Ω/cm ² or less. The shape of the conductive support may be a foil shape, a film shape, a sheet shape, a mesh shape, a punched shape or a developed shape, or a metal mesh body, a porous body, a foamed body, or a formed body of a fiber group. The thickness of the conductive support is not particularly limited, and is usually 0.1 to 10 mm.

a method of providing a semiconductor-containing layer containing metal oxide fine particles on a conductive support (hereinafter also referred to as a substrate), and a method of forming a thin film formed of oxide semiconductor fine particles directly on a substrate by vapor deposition; The substrate is an electrode, and a layer of the oxide semiconductor fine particles is electrically deposited on the substrate; a slurry or a paste containing the metal oxide fine particles is prepared, and the layer is coated on the substrate, and then dried, hardened, or burned. The method of formation. Among them, a method of using a slurry is preferred. The slurry is obtained by dispersing a metal oxide semiconductor which has been agglomerated twice using a dispersing agent in a dispersion medium to have an average primary particle diameter of 1 to 3000 nm. Further, the slurry is obtained by hydrolyzing a metal alkoxide or the like of a precursor of an oxide semiconductor by hydrolysis reaction of an alkoxide metal in an alcohol.

The dispersing agent used for preparing the slurry can be used without any particular limitation as long as the metal oxide fine particles can be dispersed. Specifically, an alcohol such as water or ethanol, a ketone such as propanol or acetamidineacetone, or an organic solvent such as a hydrocarbon such as hexane which is not ionic can be used. These can be mixed and used. The use of water reduces the viscosity change of the slurry and is extremely suitable.

A dispersion stabilizer may be added for the purpose of obtaining primary particles of a stable metal oxide in the slurry. Specific examples of the dispersion stabilizer which can be used include polyhydric alcohols such as polyethylene glycol; condensates of polyhydric alcohols such as polyethylene glycol and phenol, octanol, etc.; hydroxypropylmethylcellulose, hydroxymethylcellulose, a cellulose derivative such as hydroxyethyl cellulose or carboxymethyl cellulose; polypropylene decylamine; poly(meth)acrylic acid or a salt thereof; poly(meth)acrylic acid or a salt thereof; acrylamide and (methyl) a copolymer of acrylic acid or an alkali metal salt thereof; (a) an alkali metal salt of acrylamide and/or (meth)acrylic acid; and (b) methyl (meth)acrylate, ethyl (meth)acrylate, etc. ( a water-soluble acrylic derivative of a copolymer of a methyl acrylate or a hydrophobic monomer such as styrene, ethylene or propylene; a salt of a melamine sulfonic acid formaldehyde condensate; a salt of a naphthalene sulfonic acid formaldehyde condensate; Lignosulfonate; acid such as hydrochloric acid, nitric acid, acetic acid; There are no restrictions on such dispersion stabilizers. Further, these dispersion stabilizers may be used alone or in combination of two or more.

Among these, polyhydric alcohols such as polyethylene glycol; condensates of such polyols with phenol, octanol, etc.; those having a carboxyl group and/or a sulfo group and/or a mercapto group in the molecule; poly(methyl) Poly(meth)acrylic acid such as acrylic acid, sodium poly(meth)acrylate, potassium poly(meth)acrylate or poly(methyl)acrylate or a salt thereof; carboxymethylcellulose; acid such as hydrochloric acid, nitric acid or acetic acid good.

The concentration of the metal oxide fine particles in the slurry is from 1 to 90% by weight, preferably from 5 to 80% by weight. The method of applying the slurry containing the metal oxide fine particles to the substrate is not particularly limited. A method in which a glass rod is applied to a desired thickness, a screen printing method, a coating by a spin method, or a spray method by a spray method can be employed.

It is preferred that the substrate coated with the slurry is subjected to a baking treatment. The firing temperature is about not higher than the melting point (or softening point) of the substrate, and is usually from 100 to 900 ° C, preferably from 100 to 600 ° C (but below the melting point or softening point of the substrate). Further, the firing time is preferably within 4 hours. Further, the thickness of the coating slurry on the substrate is usually from 1 to 200 μm, preferably from 3 to 100 μm. The thickness of the layer of the metal oxide fine particles (semiconductor-containing layer) which has been subjected to the treatment such as drying or baking is usually 0.01 to 180 μm, preferably adjusted to 0.05 to 80 μm.

For the purpose of improving the surface smoothness of the semiconductor-containing layer, the metal compound can be used for two treatments (see Non-Patent Document 2). The metal compound can be directly impregnated into each of the substrates, such as alkoxide, chloride, nitrate, sulfide, metal acetate, etc., in the same metal as the metal granules of the metal oxide, and dried. The demand is improved by smoothing. Metal alkoxides, such as titanium ethoxide, titanium isopropoxide, titanium t-butoxide, etc.; oxides, titanium tetrachloride, tin tetrachloride, zinc oxide, etc.; metal acetates, di-n-butyl Base diacetyl fluorenyl and the like. These metal compounds can be used by being dissolved and suspended in a solvent such as water or alcohol.

Next, a method of loading a dye for sensitization of a semiconductor-containing layer provided on the conductive support as described above will be described.

By absorbing (loading) the dye for sensitization of the semiconductor-containing layer prepared by the metal oxide fine particles, the function of converting the light energy absorbed by the semiconductor-containing layer into electric energy can be imparted. The sensitizing dye can be used without any particular limitation in order to absorb light sensitized with metal oxide fine particles. A well-known sensitizing dye or the like which is well known in the art, such as a metal complex dye or a non-metal organic dye, can be used. The pigments used may be used alone or in combination of several kinds. Further, in the case of mixing, the organic dyes may be mixed with each other, or may be a mixture of an organic dye and a metal-coordinated dye. In particular, by absorbing a mixture of dyes having different wavelengths, it is possible to obtain a dye-sensitized photoelectric conversion element having a high conversion efficiency by using a wide absorption wavelength. Examples of the metal complex dye which can be used include a ruthenium complex, a phthalocyanine dye, and a porphyrin dye. Further, examples of the non-metallic organic pigments include non-metallic phthalocyanine dyes, non-metallic porphyrin dyes, cyanine dyes, phthalocyanine dyes, oxo alcohol dyes, and triphenylmethane dyes. A pigment such as an acrylic dye, a xanthene dye, an azo dye, an anthraquinone dye, or an anthraquinone dye. Preferred are methine-based dyes such as ruthenium complexes or merocyanine dyes and acrylic dyes. The ratio of the respective pigments when the pigments are used in combination is not particularly absorbed, and the optimum conditions are appropriately selected from the respective dyes. In general, it is preferred to use a coloring matter of 10 mol% or more from the mixing of the molybdenum. When a solution containing two or more kinds of dyes dissolved or dispersed is used, when the semiconductor-containing layer is loaded with a dye, the total concentration of the dye in the solution can be the same as in the case of only one type of the dye. When the solvent is used in combination, the solvent described below may be used, and the solvent used for each coloring agent may be the same or different.

In the method of supporting the dye-containing layer in the semiconductor-containing layer, a solution obtained by dissolving each of the above-mentioned dyes in a solvent described below or a dispersion obtained by dispersing a dye having a low solubility is immersed in the metal oxide fine particles. A method in which a semiconductor contains a substrate of a layer or the like. The impregnation temperature is about 20 ° C to the boiling point of the solvent used. Further, the immersion time is usually from 1 to 48 hours. Specific examples of the solvent used for dissolving the dye include methanol, ethanol, acetonitrile, dimethyl hydrazine, dimethylformamide, and t-butanol. The dye concentration of the solution, at molar concentration (M) basis, generally 1 × 10 ^{- 6} M ~ 1M preferably, more preferably ^{1 × 10 - 5 M ~ 1} × 10 - 1 M.

When the dye is supported on the semiconductor-containing layer formed of the metal oxide fine particles by the immersion method as described above, it is more suitable to carry out the treatment in the coexistence of the inclusion compound in order to prevent aggregation of the dyes. Examples of the inclusion compound used herein include deoxycholic acid, goose (deoxy)cholic acid, methyl cholate, sodium cholate, and the like, crown ether, cyclodextrin, Calicus alen, polycyclic ring. Oxyethane and the like. Preferred are deoxycholic acid, goose cholic acid, methyl cholate, sodium cholate and the like, polyethene oxide and the like. Further, after the dye is loaded, the semiconductor-containing layer can be treated with an amine compound such as 4-tert-butylpyridine. As a method of the treatment, for example, a method in which a substrate on which a semiconductor-containing layer containing a dye is placed is immersed in an ethanol solution of an amine can be used. After the immersion treatment and the post-treatment are completed, the solvent is removed by air drying or heating, and the substrate containing the semiconductor layer containing the dye is provided.

In the present invention, a semiconductor-containing layer can be formed on a substrate by applying a dye to the metal oxide fine particles and then applying the dye to the substrate.

The metal oxide fine particle film (semiconductor-containing layer) of the dye-supported dye thus prepared is a function as a semiconductor electrode in the photoelectric conversion element of the present invention.

Next, in the photoelectric conversion element of the present invention, FTO conductive glass, aluminum, titanium, stainless steel, nickel, fired carbon, conductive polymer, conductive glass or the like is used as the counter electrode. Others, for the purpose of improving adhesion, conductivity, and oxidation resistance, on the surface of a conductive support having a surface such as aluminum, copper or the like treated with carbon, nickel, titanium or silver, vapor deposition is used for the redox-based electrolyte pair. The reduction reaction has platinum, carbon, ruthenium, osmium and the like which assist the catalysis. Further, a person who applies and heats a conductive fine particle optical drive can also be used.

In the method of producing a photoelectric conversion element of the present invention, for example, a sealing portion is formed around a conductive support, and a semiconductor-containing layer sensitized with a dye is disposed as a semiconductor electrode. Next, for example, after a spacer member such as a glass fiber is added to a sealant for an ultraviolet-ray curing type photoelectric conversion element, a part of the charge-transfer layer is left by a screen printing or a disperser around the semiconductor electrode. Injection inlet, coated with sealant. Thereafter, the solvent is evaporated, for example, by heat treatment at 100 ° C for 10 minutes. Next, another conductive support such as platinum is placed on the conductive surface so as to be superposed on the conductive surface, and is bonded by a compressor, and is irradiated with ultraviolet rays of, for example, 3,000 mJ/cm ² using a high pressure mercury lamp. According to the demand, for example, it can be hardened after 10 minutes at 120 °C.

The gap provided between the two conductive supports serves as a charge transporting layer. This gap is usually from 1 to 200 μm, preferably from 3 to 100 μm.

In the gap between the two conductive supports, the charge transport layer is formed by injecting the electrolyte composition for a photoelectric conversion element of the present invention from the injection port, and then the injection port is closed to obtain the photoelectric conversion element of the present invention.

The solar cell of the present invention is obtained by interposing a resistance component between the positive electrode and the negative electrode of the photoelectric conversion element of the present invention.

[Examples]

The invention is illustrated in more detail by way of examples.

[Example 1] (modulation of electrolyte composition)

1-ethyl-3-methylimidazolium chloride and LiN(SO ₂ CF ₃ ) ₂ are reacted in water in an equimolar ratio to obtain 1-ethyl-3-methylimidazolium bistrifluoromethane Sulfonyl imine. In a mixed solvent in which 3-methoxypropionitrile (3/1 by weight) is mixed, respectively, dissolved and mixed as a redox-based electrolyte, 1,2-dimethyl-3-propylimidazolium iodide/iodine The electrolyte composition 1 of the present invention was obtained at 0.5 M/0.05 M.

[Examples 2 to 44], [Reference Examples 1 to 12] (modulation of electrolyte composition)

As in Example 1, the respective compositions shown in Table 1 were used, that is, the electrolyte compositions of the present invention were respectively obtained (the electrolyte compositions of Example 1 are also shown in Table 1).

Each symbol, abbreviation, and the like in Table 1 are as described below.

<Electrolyte Pair> (redox electrolyte pair) A: 0.5 M 1,2-dimethyl-3-propylimidazolium iodide, 0.05 M iodine, B: 0.5 M tetrapropylammonium iodide, 0.05 M iodine , C: 0.5 M trimethyl propyl ammonium iodide, 0.05 M iodine, <Crystal temperature molten salt (S) cation > EMI ⁺ : 1-ethyl-3-methylimidazolium cation TMAP ⁺ : Trimethyl propyl Alkyl ammonium cation TMMMA ⁺ : trimethyl methoxymethyl ammonium cation MPI ⁺ : 1-methyl-3-propyl imidazolium cation MHI ⁺ : 1-methyl-3-hexyl imidazolium cation BP ⁺ :N- Butylpyridinium cation EMP ⁺ : 1-ethyl-2-methylpyrroleium cation <anion of normal temperature molten salt (S)>TFSI ^- :N(SO ₂ CF ₃ ) ₂ ^- : bistrifluoromethanesulfonyl Yttrium imine, DCA ^- :N(CN) ₂ ^- : dicyanoguanamine anion, TSAC ^- :N(SO ₂ CF ₃ )(COCF ₃ ) ^- :trifluoro-N-trifluoromethanesulfonyl Indoleamine, TfO ^- :CF ₃ SO ₃ ^- : trifluoromethanesulfonyl anion

I ^- : iodide anion,

<Organic solvent (T)> (non-ionic organic solvent)

3-MPN: 3-methoxypropionitrile,

PC: propylene carbonate

EC/AN: ethylene carbonate / acetonitrile (6/4)

MMO: 3-methyl-2-oxazolidinone

BC: Butylene carbonate

γ-BL: γ-butyrolactone

MAN: methoxyacetonitrile

EG: ethylene glycol

Further, in Table 1, the mixing ratio (S/T) of the room temperature molten salt (S) and the organic solvent (T) is a weight ratio. Further, the viscosity was measured by a viscosity meter (TVE-20, manufactured by Toki Sangyo Co., Ltd.).

[Example 45] (Production of photoelectric conversion element)

Here, reference is made to FIG. 1 . Nitric acid (dispersant) 0.9 m l was added to 8 g of titanium oxide (P-25, manufactured by Ayello Gyro, Japan, average primary particle size 21 nm), placed in a mortar for dispersion and kneading, and 20 m was added at the same time. l After the water, a few drops of a dispersion stabilizer (Triton X-100, manufactured by Arrudoli Co., Ltd.) was added to obtain a white paste. Then, the paste was uniformly applied to a conductive surface of a fluorine-doped tin oxide glass (FTO glass, manufactured by Asahi Glass Co., Ltd.) of the conductive support 1 by a glass rod to obtain a semiconductor-containing layer 2. After air drying for 1 hour, it was baked at 450 ° C for 30 minutes to obtain a semiconductor thin film electrode (A). Thereafter, it was naturally cooled to about 100 ° C, and immersed in an EtOH solution (3 × 10 ^-4 M) of the pigment [pigment (1)] represented by the following formula (1) at room temperature for 1 night, followed by EtOH. Wash and dry naturally. Next, a conductive surface of a fluorine-doped tin oxide glass (FTO glass, manufactured by Asahi Glass Co., Ltd.) of the conductive support held by the semiconductor-containing layer 2 to which the dye is adsorbed is provided with a gap of 10 μm by sputtering. The oppositely disposed platinum layer is opposite to the electrode 3. Next, the semiconductor layer containing the dye, the platinum layer counter electrode 3 which is provided by sputtering on the conductive surface of the fluorine-doped tin oxide glass (FTO glass, manufactured by Asahi Glass Co., Ltd.) of the conductive support , the relative arrangement by the sealing agent bonding. The electrolyte composition obtained in Example 1 was injected as a charge transporting layer in the void thereof to obtain the photoelectric conversion element of the present invention.

[Example 46] (Preparation of titanium oxide fine particles by a sol-gel method)

The production of titanium oxide fine particles by a sol-gel method was carried out. 30 g of titanium isopropoxide was used as the titanium alkoxide, which was suspended in 150 ml of water as a solvent, and sealed in a heat of 300 m 1 . After replacing the autoclave with nitrogen gas, the temperature was raised to 230 ° C for 12 hours. After completion of the reaction, it was naturally cooled to obtain a suspension containing 8.4 g of titanium oxide fine particles.

The suspension of the obtained titanium oxide fine particles was adjusted to a paste with terpineol, and uniformly coated on the conductive surface of the same conductive support as described in Example 45 using a glass rod, and air-dried for 1 hour at 450 ° C. After firing for 30 minutes, the semiconductor thin film electrode (B) was obtained. As the semiconductor thin film electrode (B), the electrolytic solution composition obtained in Example 2 was used as the charge transporting layer, and other conditions were carried out in the same manner as in Example 45 to obtain the photoelectric conversion element of the present invention.

[Example 47] (Production of polished titanium oxide fine particles)

The production of polished titanium oxide fine particles (Ti/Zr) was carried out. Titanium alkoxide (25 g of titanium isopropoxide) and 18.2 g of zirconium isopropoxide were used as zirconium alkoxide, and the mixture (Ti/Zr atomic ratio = 1/0.3) was suspended in a solvent of 1, The 4-butanediol 130 m l was sealed in an autoclave with a capacity of 300 m l . After replacing the autoclave with nitrogen gas, the temperature was raised to 300 ° C for 2 hours. After completion of the reaction, it was naturally cooled to obtain 150 ml of a suspension containing 13.7 g of fine titanium oxide fine particles.

The suspension of the obtained polished titanium oxide fine particles (Ti/Zr) was adjusted to a paste with terpineol, and uniformly coated on the conductive surface of the same conductive support as described in Example 45 using a glass rod, and air-dried 1 After an hour, it was baked at 450 ° C for 30 minutes. Thereafter, a 0.05 M aqueous solution of titanium tetrachloride was dropped on the titanium oxide fine particles, and the mixture was treated at 80 ° C for 10 minutes, and then baked at 450 ° C for 30 minutes to obtain a semiconductor thin film electrode (C). This semiconductor thin film In the electrode (C), the electrolytic solution composition obtained in Example 3 was used as the charge transporting layer, and other conditions were carried out in the same manner as in Example 45 to obtain the photoelectric conversion element of the present invention.

<Measurement of the production and transformation ability of solar cells>

In the positive electrode and the negative electrode of the photoelectric conversion element obtained in Examples 45 to 47, a lead wire was disposed, that is, a solar cell of the present invention was obtained. This solar cell was connected to a solar simulator (WXS-155S-10, manufactured by WACOM Co., Ltd.) described below, and the short-circuit current, the open voltage, and the conversion efficiency were measured. Further, the size of the photoelectric conversion element supplied to the measurement was 0.5 × 0.5 cm. Further, the light source used was a 1,000 W xenon lamp (manufactured by WACOM Co., Ltd.), and a commercially available Air mass 1.5 filter was used as the pseudo-sunlight (light intensity: 100 mW/cm ² ).

The measurement results of the short-circuit current, the open voltage, and the conversion efficiency of each solar cell are shown in Table 2.

[Examples 48 to 52], [Reference Examples 13 to 15]

Each of the semiconductor thin film electrodes (A), (B) and (C) obtained in Examples 45 to 47, the dye (1) represented by the above formula (1), and the following formulas (2) and (3) were used. The dye (2) and the dye (3), the respective electrolyte compositions obtained in the examples 4, 7, 14, 24, 40 and the reference examples 1, 2, and 5 were prepared by modulating a photoelectric conversion element; battery. With respect to these solar cells, the short-circuit current, the open voltage, and the conversion efficiency were measured in the same manner as in Examples 45 to 47.

The components used and the results obtained are shown in Table 2.

The numbers in the electrolyte composition column of Table 2 are intended to be the electrolyte compositions obtained in the examples. Further, the dye is a dye of the above formula (1), a dye (2) represented by the following formula (2) and the formula (3), and a dye (3). Further, (A), (B) and (C) in the column of the semiconductor thin film electrode are intended to be the respective semiconductor thin film electrodes obtained in Example 45, Example 46 and Example 47.

As is clear from the results of Table 2, the solar cell produced by using the electrolytic solution composition of the present invention has sufficient open voltage and excellent conversion efficiency.

Further, a solar cell was produced by the photoelectric conversion element obtained in Example 2, and when it was exposed to sunlight for 80 days, the conversion efficiency of 98% of the initial value was shown. From this, it is understood that the photoelectric conversion element (solar cell) of the present invention is excellent in durability.

[Example 53] (Production of durable battery)

In a mixed solvent of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonylimine and 3-methyl-2-oxazolidinone (weight ratio 9/1), Dissolving 1,2-dimethyl-3-propylimidazolium iodide/iodine as an electrolyte to form 0.5M/0.05M, respectively, to obtain an electrolyte composition (except for normal temperature molten salt/non-ionic organic solvent) The composition of the electrolyte of Example 6 was the same as the ratio). An injection port of the electrolyte composition was placed on the counter electrode of Example 45, and the semiconductor film electrode and the counter electrode were bonded together with a sealant (Haijimlan, manufactured by Mitsui DuPont Polymer Chemical Co., Ltd.). Thereafter, the electrolyte composition as the charge transporting layer was injected from the injection port, and the injection port was sealed with a sealant, and other conditions were carried out in the same manner as in Example 45 to prepare a photoelectric conversion element. Here, a wire is disposed between the positive electrode and the negative electrode of the photoelectric conversion element, that is, a solar cell is obtained. This solar cell was connected to a solar simulator (WXS-155S-10, manufactured by WACOM Corporation), and the conversion efficiency was measured. Further, the size of the photoelectric conversion element supplied to the measurement was 0.5 × 0.5 cm. Further, a 1,000 W xenon lamp (manufactured by WACOM Co., Ltd.) was used as a light source, and a commercially available Air mass 1.5 filter was used as the pseudo-sunlight (light intensity: 100 mW/cm ² ). The photoelectric conversion efficiency of this photoelectric conversion element did not largely change during a 60-day operation at a certain temperature (25 ° C, 80 ° C).

[Comparative Example 1] (The same as the electrolyte composition of Example 2 of Patent Document 4 except for the molar concentration of lithium iodide/iodine)

In a mixed solvent prepared by mixing 1-hexyl-3-methylimidazolium iodide with 3-methyl-2-oxazolidinone (weight ratio 1/2), iodination is separately dissolved and mixed as an electrolyte. Lithium/iodine was made into 0.2 M/0.07 M to obtain an electrolyte composition. This electrolyte composition was used as a charge transporting layer, and other conditions were carried out in the same manner as in Example 53 to prepare a photoelectric conversion element, and the photoelectric conversion efficiency of the photoelectric conversion element was measured. The results of Example 53 and Comparative Example 1 are shown in Table 4.

As is clear from the results of Table 4, the solar cell produced in Example 53 had much higher durability at 80 ° C than Comparative Example 1.

[Industrial use]

The electrolyte composition for a photoelectric conversion element of the present invention is very suitable for a secondary battery such as a photoelectric conversion element or a fuel cell, a battery such as a lithium battery or an electric double layer capacitor. In particular, the photoelectric conversion element using the same and the solar cell obtained therefrom have extremely high practical value.

1. . . Conductive support

2. . . Semiconductor containing layer

3. . . Setting the counter electrode of the platinum layer

4. . . Charge moving layer

5. . . Sealants

Fig. 1 is a schematic cross-sectional view showing an essential part of an example of a photoelectric conversion element of the present invention.

1. . . Conductive support

2. . . Semiconductor containing layer

3. . . Setting the counter electrode of the platinum layer

4. . . Charge moving layer

5. . . Sealants

Claims (9)

An electrolyte composition for a photoelectric conversion element, characterized by comprising 1,2-dimethyl-3-propylimidazolium iodide and iodine, tetrapropylammonium iodide and iodine, and trimethylpropylammonium a redox electrolyte pair selected from the group consisting of iodide and iodine; from 1-ethyl-2-methylpyrrole N(SO ₂ CF ₃ )(COCF ₃ ) ^- , trimethylmethoxy a room temperature molten salt selected from the group consisting of ammonium bistrifluoromethanesulfonyl quinone imine and N-butylpyridinium bistrifluoromethanesulfonyl quinone imine; and an organic solvent having no ionicity; The ratio of the non-ionic organic solvent is from 2 to 40% by weight based on the total weight of the normal temperature molten salt and the nonionic organic solvent. A photoelectric conversion element characterized by comprising a conductive support having a semiconductor-containing layer and a conductive support having opposite electrodes disposed at a predetermined pitch, and holding a charge-transferring layer in a space between the two supports In the conversion element, the charge transporting layer contains the electrolyte composition for a photoelectric conversion element according to the first aspect of the patent application. The photoelectric conversion element according to claim 2, wherein the semiconductor of the semiconductor-containing layer is titanium oxide or modified titanium oxide. The photoelectric conversion element according to claim 3, wherein the titanium oxide or the modified titanium oxide is a particulate titanium oxide or a modified titanium oxide formed by dye sensitization. The photoelectric conversion element of claim 4, wherein the pigment is a metal complex pigment or a non-metal organic pigment. A solar cell characterized by using the photoelectric conversion element of the second application of the patent application. A solar cell characterized by using the photoelectric conversion element of claim 3 of the patent application. A solar cell characterized by using the photoelectric conversion element of claim 4 of the patent application. A solar cell characterized by using the photoelectric conversion element of claim 5 of the patent application.